1. Field of the Invention
The invention relates to a thin film magnetic head having at least an inductive magnetic transducer for writing, and a method of manufacturing the same.
2. Description of the Related Art
Recently, an improvement in performance of a thin film magnetic head has been sought in accordance with an increase in an areal recording density of a hard disk drive. A composite thin film magnetic head, which has a laminated structure comprising a recording head having an inductive magnetic transducer for writing and a reproducing head having a magnetoresistive (hereinafter referred to as MR) element for reading, is widely used as the thin film magnetic head.
For example, the recording head includes a top pole and a bottom pole which are formed on and under a write gap, respectively, with the write gap in between the top and bottom poles, and a coil for generating a magnetic flux, which is formed between the top and bottom poles with an insulating layer in between the coil and each of the top and bottom poles. The top pole and the bottom pole have the same uniform width near the write gap in a region close to a recording-medium-facing surface (i.e., an air bearing surface) to be faced with a magnetic recording medium (hereinafter referred to as “a recording medium”), and these portions constitute “a pole tip portion” for defining a write track width.
To increase a recording density of the performance of the recording head, a width of the pole tip portion (i.e., a pole width) must become extremely small to the submicron order so as to increase a track density on the recording medium. In this case, it is preferable that the pole width be uniform with high accuracy throughout the pole tip portion. A partly great pole width causes the occurrence of a side erase phenomenon: that is, information is written on not only a desired track region on which the information is to be written but also track regions adjacent to the desired track region, and thus, information previously written on the track regions adjacent thereto is overwritten with the newly written information, so that the previous information is erased.
As mentioned above, a minuter pole width also requires a reduction in a thickness of a magnetic pole in itself from the viewpoint of a problem in manufacturing, and, as a consequence, there is a tendency to make all dimensions of components (e.g., the coil, etc.) of the whole head extremely small. To favorably ensure characteristics of overwriting information on the recording medium, namely, overwrite characteristics, of the performance of the recording head, it is necessary that a sufficient amount of magnetic flux be generated by the passage of a current through the coil so as to supply the generated magnetic flux to a pole portion. However, a problem exists: that is, too small a cross-sectional area of the coil owing to the tendency to make the above-mentioned components extremely small brings too high an electrical resistance value and thus causes a reduction in the amount of current passing through the coil, so that this leads to a marked reduction in the amount of generated magnetic flux. The reduction in the amount of generated magnetic flux causes the shortage of magnetic flux for magnetizing the recording medium at the time of the recording of information and thus results in a marked deterioration in the overwrite characteristics.